1. Field of the Invention
The present invention relates to a zoom lens and an imaging apparatus. In particular, the present invention relates to a zoom lens appropriate for a digital camera, a video camera and the like, and to an imaging apparatus including the zoom lens.
2. Description of the Related Art
In recent years, as personal computers spread to ordinary families, digital cameras that can input image information, such as a landscape and a portrait, obtained by photography to personal computers became widely used. Since the function of the digital cameras became higher recently, a demand for a digital camera with a high-magnification zoom lens mounted thereon is increasing.
Therefore, for example, a zoom lens with a high magnification ratio, as disclosed in Japanese Unexamined Patent Publication No. 2007-219040 (Patent Document 1), is used. The zoom lens consists of a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power and a fourth lens group having positive refractive power, which are in this order from an object side. The magnification of the zoom lens is changed by changing distances between the groups. Japanese Unexamined Patent Publication No. 2003-207715 (Patent Document 2) discloses a zoom lens with similar basic structure to that of Patent Document 1. Patent Document 2 discloses, as a four-group zoom-type zoom lens with a high magnification ratio, a zoom lens having a small Fno. at a wide angle end while achieving a high variable magnification ratio. Japanese Unexamined Patent Publication No. 2010-217478 (Patent Document 3) discloses a zoom lens having excellent optical performance while achieving a high magnification ratio.